Head-to-head, or H2H, is the record between two players across every prior meeting. It answers the first question anyone asks before a match: when these two have played, who usually wins?
Why it matters beyond the raw level
Elo tells you which player is stronger overall, but two specific players can have a lopsided history that their ratings don't predict. This is often a style matchup effect, where one player's game consistently troubles the other. A 6-1 head-to-head in favor of the lower-rated player is exactly the kind of signal that pure ratings miss.
Reading H2H carefully
The record is most useful when the meetings are recent and on a comparable surface. Five matches from a decade ago, or a clay-heavy history before a grass match, say less than a small but recent and surface-matched sample. The model weighs H2H as one input among many rather than treating it as destiny.
Compare any two players, overall and by surface, with the head-to-head tool.